I can't program, but i enjoy using the rockbox audio compressor as a device, in that I keep a few older gen IPOD mini's for hooking up to things say an FM transmitter or party speakers, using the compressor as both a protection thing and a "don't irritate the neighbours" type thing.
How difficult would it be to export the code to say an Arduino or Rpie for near realtime in->out with configuration ability - i have no idea how to do it, the first software compressor I used was the tomass limiter and it's cousin the "sound solution" plugins for winamp.